It certainly is not worth the hefty price, but they can detect eggs, some protozoa and or fungi easily.
If it were me, I would use multiple immuno assays, and some tests to detect cryptocidin and other LMP's in the sample.
Technology allows this, and it is becoming cheaper and more available.
The problem is, labs don't want to risk going into complex tests for fear of making higher scores on detection.
It is way easier for a lab to miss things than to catch things, from a legal point.
Fear of litigation has the entire health industry working on a philosophy of avoidance.
If it is a parasite like mine, there is no chance for detection. Shroom